Stop
Never open a hot radiator cap or coolant reservoir; pressurized hot coolant can cause severe burns. Pull over and shut off the engine as soon as it's safe.
Symptoms
- Temperature gauge needle in the red or a red thermometer icon lit
- Steam or a burning smell from under the hood
- Possible loss of power or rough running
Likely causes
- CommonLow coolant level from a leakCoolant leaks from hoses, the radiator, or a water pump are the most common cause.
- CommonFailed thermostat stuck closedBlocks coolant flow to the radiator, causing rapid overheating.
- PossibleFailing water pumpCan't circulate coolant even if the level is fine.
- PossibleCooling fan not runningEspecially noticeable at idle or in slow traffic when airflow is low.
- Less commonBlown head gasketMore serious and often follows repeated overheating episodes.
What to do
- Turn off the AC and turn the heater to full hot to pull heat away from the engine.
- Pull over safely as soon as possible and shut the engine off.
- Do not open the radiator cap or coolant reservoir while the engine is hot; pressurized coolant can cause severe burns.
- Let the engine cool for at least 20–30 minutes before checking anything under the hood.
- Once cool, check the coolant reservoir level and look for obvious leaks, puddles, or a burnt-coolant smell.
- If coolant is low and no obvious leak is visible, add the correct coolant mix and monitor the temperature closely afterward.
- If the gauge climbs again quickly or you see a leak, do not keep driving; call for a tow.
- Have a mechanic diagnose the specific cause before driving any real distance.
Tools and parts
Coolant/antifreeze, correct type for your carSearch: “coolant type for your car make and model”
When to call a pro
See a mechanic before driving further if the engine has overheated; continuing to drive risks a cracked head or blown gasket.
Safety
Stop
Never open a hot radiator cap or coolant reservoir; pressurized hot coolant can cause severe burns. Pull over and shut off the engine as soon as it's safe.